Retinal detachment (RD) is a serious ocular condition in which the retina is separated from its underlying tissues. Retinal detachment is a common cause of severe vision loss. In retinal detachment, the retina pulls away from the underlying tissue layers which provide oxygen and metabolic support. Retinal detachment can occur when vitreous fluid leaks through a retinal hole or tear and collects underneath the retina. Tears or holes in the retina can occur for a number of reasons including disorders or aging that causes the retina to thin. A tear typically develops when there is a sudden collapse of the vitreous thus causing tugging on the retina with enough force to cause a tear. Fluid inside the vitreous may then travel through the tear and collect under the retina thus peeling it away from the underlying tissues which provide oxygen. In areas in which the retina is detached and the cells lack oxygen, vision may be lost if not treated quickly.
Rhegmatogenous retinal detachment is the most common etiology and is caused by a tear or hole that is usually in the peripheral retina.
Retinal detachment itself is painless, however symptoms are usually present before it occurs or advances. Symptoms of retinal detachment include the appearance of a large number of floaters; sudden flashes of light in the affected eye; and a shadow over a portion of the visual field that develops as the detachment progresses. Several conditions may increase the chance of retinal detachment including nearsightedness; previous cataract surgery; eye trauma; previous retinal detachment in the other eye; family history of retinal detachment; or weak areas in the retina. If left untreated, there is a very high chance of permanent vision loss.
Surgical repair, often emergent, is necessary to treat retinal detachment. Pars plana vitrectomy is the most commonly used method to repair RD. Vitrectomy involves removal of vitreous and all other tractional forces exerted on the torn retina and drainage of subretinal fluid, after which the eye is filled with a solution, such as a sterile saline solution. A fluid-gas exchange procedure is then performed in which the saline solution is removed at the same volumetric rate as a gas is injected. As the gas replaces the fluid, any subretinal fluid is squeezed from under the retina and can be removed with an extrusion cannula. Once all the saline solution is removed, the retinal tear or hole is treated using laser photocoagulation or cryoretinopexy. Finally, the fluid in the vitreous cavity is drained and replaced with either an expansive gas mixture or silicone oil.
Vitrectomy surgery is performed using an operating microscope, an endoilluminator probe, and a specialized wide-field lens system to allow for visualization of the retinal tissues. Sharp visualization is very important for the surgical success as precise intraoperative manipulation of tissues is required. Condensation of water or silicon droplets can develop on the posterior surface of an intraocular lens during the fluid-gas exchange can severely compromise the surgeon's view and make it difficult to impossible to see and repair the retinal detachment. Also, patients that have had a detached retina repaired using silicone oil can later develop adherent silicone oil bubbles to the posterior surface of their intraocular lens which can cause very blurred vision.
There are several strategies to deal with intraoperative lens condensation, none of which are very effective. Similarly, there are no simple methods to treat silicone oil bubbles adherent to an intraocular lens implant.
One strategy to deal with intraoperative lens condensation is the use of an aspiration cannula to remove the condensation. (Jaffe, 1997). In this method, the posterior surface of the intraocular lens is wiped with a soft-tipped aspiration cannula, or suction tube, which then aspirates the condensation through the cannula and out of the surgical field. This method only partially cleared the condensation in 6 of the 11 patients in which condensation occurred, however the condensation quickly reappeared to completely obscure the surgeon's vision after only a few minutes. Also, the tube is not specifically designed for this task. The suction tube is flaccid and does not allow for precise control or firm displacement.
Another method suggested injecting a balanced salt solution onto the posterior surface of the lens. However, this approach requires injecting fluid into a space in which the surgeon is trying to remove fluid. (Sappenfield, 1989)
Saperstein (U.S. Pat. No. 5,919,158) discloses an infusion cannula for use in clearing and preventing condensation on the posterior surface of an artificial lens during the fluid-gas exchange portion of a pars plana vitrectomy. In use, the infusion cannula redirects the flow of gas entering the eye toward the posterior surface of the lens with the moisture content and temperature of the gas supplied to the infusion cannula being controlled.
Using an intraocular irrigating solution or filling the anterior chamber of the eye with a warm viscoelastic fluid to warm the lens has been suggested to prevent condensation. However, these solutions require the constant manipulation of instruments to deliver the solution/fluid during surgery and can leave a film of the fluid on the posterior lens which distorts the surgeon's view.
Recently, a heating pad has been placed over the eye with lids closed for approximately 20 minutes to reduce condensation to allow the application of laser retinopexy. However, while the condensation was reduced in order to finish the surgery, the condensation reoccurred on the intraocular lens once the eye cooled thus not making this an effective solution. (Browning, 2005)
Given the disadvantages in the current techniques for dealing with intraoperative lens condensation, what is needed is a device and method which would allow for removal of intraoperative lens condensation.